Mitsubishi ship crane slewring bearing changeout

Alatas supplied and carried out a slewring changeout for an MHI marine crane in Piraeus, Greece.

Crane slewing gearboxes were loosened to allow free movement of slewing pinion during crane lift. On removal the slewing motors were checked for leakage.

Crane boom pivot mounting bolts removed after boom secured by floating crane. Boom removed and secured onto vessel. New slewing bearing brought onboard by floating crane. Internal and external ladder and drain pipes removed prior to tower lift. Crane slipring disconnected to to allow crane removal. Crane tower removed and place on deck. Slewbearing bolts removed allowing old slew bearing to be removed by floating crane. Inner surface of crane pedestal found to be badly scored and grooved with large amounts of metal fragments. Pedestal surface degreased and damage inner surface repaired. Pedestal underside also checked and repaired. Pedestal flatness check carried out by external contractor. New crane bearing lifted and place on crane pedestal by floating crane. Bearing secured. Floating crane used to lift pedestal into position. Pedestal bolted down, slip ring reconnected and tested for continuity. Slewing pinion check for correct fitting and alignment.

Crane jib lifted and fitted to pinions on crane tower by floating crane. Internal and external ladders refitted. Hoisting and luffing ropes refitted, slewring bearing greased. Slewing, slewring bearing and axial clearance and slewing pinion backlash check carried out. Limit switches reconnected and tested. Overload test carried out by Surveyor.